Mopar R3 Block

You can drive a 48* block on the street.
You can run a Hyd cam & lifter in a R3 if it is a 59* block.
The revised 48* tappet angle is only to straighten out the pushrod angle for better geometry. You need a special cam blank to be custom ground for the 48* block.

The revised 48* tappet angle is the way the OE blocks should have been made. Better geometry with higher rpm capabilities. (That and a better rpm capable oiling system would have been great as a delivered OEM block.)

The 48* cam core blanks, IIRC, were being sold for $300. Then you mail it to a grinder, pay him to grind it and have it mailed back to you.

The 48* heads have pushrod clearances machined into them. They can be easy to see. The machined area is against the inside wall where the intake bolts up. The machined area is deep enough to mildly cut into the valve cover gasket sealing area.